1. Field of the Invention
The present invention relates to an electronic device having a memory cell comprising a resistive storage element which can be switched between a first storage state having a first conductivity and a second storage state having a second conductivity.
2. Description of the Related Art
In contrast to static random access memories (SRAM) and dynamic random access memories (DRAM), non-volatile memory devices preserve the stored information even if they are not supplied by electrical energy. They combine the advantages of random access memories (no mechanics and almost instant access to any bit of information) with advantages of hard disk drives and other permanent storage media (long-term storage without power consumption). Thus, non-volatile random access memory devices are advantageous for many applications, and high effort is made in their development and improvement.
A number of non-volatile random access memory technologies exist, each of which provides specific advantages and disadvantages. Several particularly advantageous and promising technologies use resistive storage elements. Each storage element can be switched between a first storage state having a first conductivity and a second storage state having a second conductivity. Each of the storage states represents a “0” or a “1”. Information is written to the storage element by means of a localized magnetic field (MRAM; based on the magneto-resistive effect), by a thermally induced or supported phase change (PCRAM; based on materials existing in two different crystallographic phases with differing resistances) or by a generation or degradation of conductive bridges in an otherwise insulating material (CBRAM; based on an induced migration of ions into a material or a remigration out of the material).
In an idle state of the memory cell, the cell transistor coupled between the resistive storage element and a bit line is in a highly resistive OFF-state. If the conductivity of the resistive storage element is very low in one of the storage states, in this storage state and the idle state of the memory cell, the memory cell comprises a floating node between the resistive storage element and the transistor. The potential of this floating node is easily influenced by electromagnetic fields and particularly by potentials of adjacent conductors. The influenced potential may induce an unintentional change of the storage state of the resistive storage element, thereby corrupting the information stored in the resistive storage element.